Sulfoaluminate belite (SAB) cements from industrial by-products Sada Sahu BASF Construction Chemicals 23700 Chagrin Blvd., Cleveland, OH-44122
Phase composition of portland cement clinker C-S-A-F (CaO-SiO 2 -Al 2 O 3 -Fe 2 O 3 ) C 3 S C 2 S C 3 A C 4 AF Lime contents (%): C 3 S = 73.7 C 3 A = 62.2 C 2 S = 65.1 C 4 AF = 46.2 Total lime content = 65-70%
Energy requirement for portland cement production Portland cement production is a highly energy consuming process Clinkerization process takes place at about 1450 0 C Fuel energy = 3000 kj/kg (2000 kj/kg chemical reaction + 1000 kj/kg heat losses) major energy consumption is in the decarbonation process of calcite Electrical energy = 110 kwh/t (396 kj/kg 990 kj/kg fuel energy) major electrical energy consumptions are in clinker and raw material grinding g
Phase composition of sulfoaluminate belite (SAB) clinker C-S-A-F- (CaO-SiO 2 -Al 2 O 3 -Fe 2 O 3 -SO 3 ) C 2 S S _ C 4 A 3 C 4 AF C S S _ S _ Lime contents: C 2 S= 65.1 C 4 AS 3 =367 36.7 C 4 AF = 46.2 C S _ = 41.2 S _ Total lime content = 50-55% 55% (40-45% 45% lime from limestone)
Energy requirement for SAB cement production Clinkerization process takes place at about 1200 0 C Fuel energy = significantly lower than 3000 kj/kg (less lime to decarbonate + less heat losses) Electrical energy = significantly lower than 110 kwh/t (processed or semi processed by-products + softer clinker)
Phase compatibility in the system C-A-S* C A C 2
Phase compatibility matrix Phases 1 2 3 4 5 6 7 8 9 10 11 1 C _ 0 1 1 1 1 1 0 0 1 1 2C 3 A _ 0 1 1 1 1 0 1 1 1 3C 12 A 7 _ 0 1 1 1 0 1 1 1 4 CA _ 0 1 1 0 1 1 1 5CA 2 _ 0 1 0 1 1 1 6 CA 6 _ 0 0 1 1 1 7 A _ 0 0 0 1 8C 4 A 3 S* _ 0 1 1 9 CS* _ 0 0 10 AS 3 * _ 0 11 S* _ 0 = compatible, 1 = not compatible
Phase assemblage in the system C-A-S* 1. C-C C 3 A-C 4 A 3 S* 2. C-C 4 A 3 S*-CS* 3. C 3 A-C 12 A 7 -C 4 A 3 S* 3 12 7 4 3 4. C 12 A 7 -CA-C 4 A 3 S* 5. CA- CA 2 -C 4 A 3 S* 6. CA 2 -CA 6 -C 4 A 3 S* 7. CA 6 -A-C 4 A 3 S* 8. A-C 4 A 3 S*-CS* 9. A-CS*-AS 3 * 10. CS*-AS 3 *-S*
Change in phase composition CAC1
Phase compatibility in the system C-S-A-S*
Phase compatibility matrix in the system C-S-A-F-S* relevant to SAB cement Phases 1 2 3 4 5 6 7 8 9 10 11 12 13 14 1 C 2 S _ 0 0 0 0 0 0 0 0 0 0 0 0 0 2 C _ 1 0 1 1 0 1 1 0 1 1 0 0 3C 3 S 2 _ 1 1 1 1 1 1 1 0 0 1 0 4C 3 A _ 0 1 1 1 1 0 1 1 0 1 5C 12 A 7 _ 0 1 1 1 0 1 1 0 1 6 CA _ 1 0 0 0 1 0 0 1 7C 2 F _ 0 1 0 1 1 0 0 8 CF _ 0 0 1 1 0 0 9CF 2 _ 1 0 0 0 0 10 C 4 AF _ 1 1 0 0 11 F _ 0 0 0 12 C 2 AS _ 0 0 13 C 4 A 3 S* _ 0 14 CS* _ 0 = compatible, 1 = not compatible C 2 S + CS* C 5 S 2 S* (stable 850 to 1100 0 C) C + C 2 S C 3 S ( above 1250 0 C)
Phase assemblage in the system C-S-A-F-S* S* relevant to SAB clinkers 1. C 2 S-C-C 3 A-C 4 AF-C 4 A 3 S* 2. C 2 S-C-C 2 F-C 4 AF-CS* 3. C 2 S-C-C C 4 AF-C 4 A 3 S* -CS* 4. C 2 S-C 3 S 2 -F-C 2 AS-CS* 5. C 2 S-C 3 A-C 12 A 7 -C 4 AF-C 4 A 3 S* 6. C 2 S-C 12 A 7 -CA-C 4 AF-C 4 A 3 S* 7. C 2 S-CA-CF-CF CF CF 2 -C 4 A 3 S* 8. C 2 S-CA-CF-C 4 AF-C 4 A 3 S* 9. C 2 S-CA-CF CF 2 -C 2 AS-C 4 A 3 S*
Phase assemblage in the system C-S-A-F-S S* relevant to SAB clinkers 10.C 2 S-C 2 F-CF-C 4 A 3 S*-CS* 11.C 2 S-C 2 F-CF-C 4 A 3 S*-CS* 12.C 2 S-C 2 F-CF-C C 4 A 3 S* -CS* 13.C 2 S-CF-CF 2 -C 4 A 3 S*-CS* 14.C 2 S-CF 2 -F-C 2 AS-CS* 15.C 2 S-CF 2 -F-C 2 AS-CS* 16.C 2 S-CF 2 -F-C 4 A 3 S*-CS* 17.C 2 S-CF 2 -C 2 AS-C 4 A 3 S*-CS* 18.C 2 S-F-C 2 AS-C 4 A 3 S*-CS*
SAB primarily from by-products (chemical composition of raw materials) Oxides Limestone Fly ash Gypsum CaO 53.44 3.64 32.55 SiO 2 0.36 53.65 _ Al 2 O 3 1.18 28.26 _ Fe 2O 3 0.08 7 _ SO 3 0.04 0.05 46.51 MgO 1.02 2.99 _ TiO 2 _ 15 1.5 _ LOI 42.33 2.4 20.04
Ternary yplot showing zone of SAB clinker
Phase field map of the system limestone - fly ash - gypsum
Change in phase composition in the system limestone-fly ash (no gypsum)
Change in phase composition in the system limestone-fly ash-gypsum (5%)
Proportion of raw materials Raw Mix No. Limestone Fly ash Gypsum 1 71.0 14.0 15.0 2 76.5 17.5 15.0 3 65.0 20.0 15.0 4 63.5 16.5 20.0 5 60.0 20.0 20.0 6 57.5 22.5 20.0 7 64.0 14.0 25.0 8 57.5 17.5 25.0 9 55.0 20.0 25.0 10 65.0 15.0 20.0 11 62.0 13.0 25.0
Phase composition of cements Cement No. C2S C C4AF CF2 C2AS C4A3S* CS* 1 45.2 23.8 6.8 0.0 0.0 14.8 9.5 2 52.4 14.0 78 7.8 00 0.0 00 0.0 16.9 88 8.8 3 57.4 7.4 8.5 0.0 0.0 18.4 12.8 4 52.7 10.0 8.0 0.0 0.0 16.4 12.8 5 59.6 10 1.0 88 8.8 00 0.0 00 0.0 18.4 12.0 6 56.5 0.0 0.0 3.7 12.5 14.6 12.7 7 50.0 10.1 7.7 0.0 0.0 15.0 17.0 8 57.0 11 1.1 86 8.6 00 0.0 00 0.0 17.0 16.2 9 54.0 0.0 0.0 3.6 12.3 13.3 16.8 10 49.7 14.4 7.5 0.0 0.0 15.5 13.2 11 48.0 12.8 74 7.4 00 0.0 00 0.0 14.44 17.3
Compressive strength of mortar specimen (MPa) Cement No. 1day 7 days 28 days 1 6.8 10.5 18.3 2 7.8 9 17.8 3 1.5 3 5 4 17.7 26.5 36.3 5 11.2 19 21.9 6 7.5 13 18.3 7 7.5 30.5 36.8 8 7.8 8.5 15 9 9.6 12.8 19.5 10 18.8 28 36 11 5 15.55 20
Hydration reactions of SAB cements C 4 A 3 S* + 6C + CS* + 96 H 3C 3 A(CS*) 3 H 32 C 4 A 3 S* + CS* + 32 H C 3 A(CS*) 3 H 32 + AH 3 C 2 S + H C-S-H + CH CH + AH 3 + CS* + H C 3 A(CS*) 3 H 32
SAB cements using red mud 1. S. Sahu, "Preparation of Sulphoaluminate Belite Cement from Fly Ash and Red Mud", 4th NCB International Seminar on Cement and Building Materials, VIII-12 New Delhi, Dec. 11, (1994). 2. Singh, M., Upadhayay, S. N., and Prasad, P. M., Preparation of Special Cements from Red Mud Waste management, Vol 16, pp 665-670 (1996).
SAB cements using CFBC ash/ S-rich fly ash 1. Belz G. et al, Fludized Bed Combustion Waste as a Raw Mix Component for the Manufacture of Calcium Sulphoaluminate cements (2005). 2. Bernardo, G. et al, Calcium sufoaluminate cements made from fludized bed combustion wastes (2007). 3. Arjunan, P. et al, Sulfoaluminate cement from lowcalcium and sulfur-rich and other industrial byproducts, CCR 29, 1305-1311 (1999).
SAB cements using slag 1. Ikeda, K. Cements along the join C 4 A 3 S* - C 2 S, 7 th ICCC, III-31, Paris (1980). 2. Adolfsson, D., Steelmaking slags as raw material for sulphoaluminate belite cement Ph. D. Thesis, Department of Chemical Engineering and Geosciences, Division of Process Metallurgy, Luleå University of Technology (2006).
Concluding Remarks Production of SAB cement can significantly reduce energy consumption compared to OPC. Use of processed or semi-processed by-products can further reduce the energy requirement. Phase compatibility data combined with mass balance equations can predict the phase assemblage of the cements with various raw mix proportion. This approach can be used to screen various raw materials for the suitability of SAB cement production. Cements with a wide range of properties can be produced.